XML DOM | Model

Hello folks! welcome back to a new section of our tutorial on XML DOM. In this tutorial, we are going to be studying about the XML DOM Model.

Now that we have known what DOM means, let us now discuss about DOM structure. A DOM document is a collection of nodes or pieces of information which is organized in a hierarchy. Some types of nodes may have child nodes of various types and others are leaf nodes that cannot have anything under them in the document structure. Following below is the list of node types, with a list of node types that they may have as children -

READ: XML DOM | Introduction

• Document - Element (maximum of one), ProcessingInstruction, Document Type (maximum of one), Comment.

• Text - No children.

• Attr - Text, EntityReference.

• EntityReference - ProcessingInstruction, Element, Comment, Text, EntityReference, CDATASection.

• DocumentFragment - Element, Comment, ProcessingInstruction, CDATASection, Text, EntityReference.

• Element - Element, ProcessingInstruction, CDATASection, EntityReference, Comment, Text.

• ProcessingInstruction - No children.

• Comment - No children.

• CDATASection - No children.

• Entity - ProcessingInstruction, Comment, Element, CDATASection, EntityReference, Text.

• Notation - No children.

READ: PHP | XML DOM Parser

Example

Let us consider the DOM representation of the following XML document node.xml -

<?xml version = "1.0"?>
<Company>
   <Employee category = "technical">
      <FirstName>Kennedy</FirstName>
      <LastName>Nkpara</LastName>
      <ContactNo>1234567890</ContactNo>
   </Employee>
   
   <Employee category = "non-technical">
      <FirstName>Stephanie</FirstName>
      <LastName>Francis</LastName>
      <ContactNo>1234667898</ContactNo>
   </Employee>
</Company>

Flowchart

The Document Object Model of the above XML document would be as follows -

From the above flowchart, we can conclude that -

• Node object can have only one parent node object. This occupies the position above all the nodes.

• The parent node can have multiple nodes called the child nodes. These child nodes can have additional nodes called attribute nodes. In the above example, we have two attribute nodes which are the Technical and Non-technical. The attribute nodes is not actually a child of the element node, but is still associated with it.

• These child nodes in turn can also have multiple child nodes. The text within the nodes is called the text nodes.

• The node objects at the same level are called siblings.

• The DOM identifies -
• the objects to represent the interface and manipulate the document.
• the relationship among the objects and interfaces.

READ: PHP | XML Introduction

Alright guys! This is where we are going to be rounding up for this tutorial post. In our next tutorial, we are going to be discussing about XML DOM Nodes.

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